1. Field of the Invention
The invention relates to an image capture lens and more particularly to an image capture lens structure with plural stacked and curved optical surfaces.
2. Description of the Related Art
In recent years, image capture apparatuses, such as mobile phones with photographic functions and digital cameras have become popular due to employment of solid-state image capture devices, such as CCD (charged coupled device) type image sensors, CMOS (complementary metal oxide semiconductor) type image sensors and the like, which are capable of meeting demands for higher performance and miniaturization. For such image capture devices, taking a picture is performed by forming an image of an object on a detecting surface of the image capture device so as to capture an image, and then the image data is read (i.e. output).
With the miniaturization trend for such image capture apparatuses continuing, demand for shrinking the size of the image capture lenses used therein have increased. Typically, image capture lenses used in image capture devices are constructed of a single lens. However, due to further size reduction requirements for the image capture lenses, higher optical performance of the image capture lenses than needed in the prior art are being required.
Thus, a two-piece or multi-piece structured image capture lens has been developed, which is capable of providing a higher optical performance than a single lens. Such a two-piece construction is typically composed of two lenses with different refractive powers (i.e. one of the two lenses is a positive refractive power and the other is negative refractive power) and an aperture stop (diaphragm) therebetween, in which the lens may be formed of plastic materials because they can be processed easily and manufactured at a low cost on a mass production.
However, increasing the number of the lenses for enhancing optical performance increases the optical total track (i.e. a distance from an image side focal plane to the surface of the lens which is the closest to the object side) of the image capture lenses. Thus, the two-piece or multi-piece construction tends to be longer in size when compared with the image capture lens with a one-piece construction and is counterproductive to miniaturization of image capture apparatuses. Moreover, the conventional plastic or glass lenses are fabricated by a discrete process, which assembles the lenses one by one. Thus, the throughput is low. Therefore, there is a need to develop a novel image capture lens structure capable of addressing the above problems.